Apparatus and method for protecting solid-state circuit breaker

The present application claims priority to Chinese Patent Application No. 202410038570.3, filed on Jan. 10, 2024, which is incorporated herein by reference in its entirety.

Example embodiments of the present disclosure generally relate to the field of electrical equipment, and more particularly to an apparatus and method for protecting a solid-state circuit breaker, a solid-state circuit breaker, and a computer-readable storage medium.

A circuit breaker is a switching device that is responsible for switching on and off a current in a normal circuit state and capable of closing and carrying a current in an abnormal circuit state within a specified time. A solid-state circuit breaker is a future development trend of end power distribution equipment, which realizes on-off control of a main circuit through contactless switching devices. In the solid-state circuit breaker, a transient voltage suppressor (TVS) is the most direct and effective means to protect solid-state switching devices from being broken down by a voltage generated by a line inductance. With continuous increase of a current level in the solid-state circuit breaker and the line inductance in practical application situation, an induced voltage generated by the line inductance and beared by the solid-state circuit breaker is increasing, which brings a great challenge to the life of protection devices such as the transient voltage suppressor. In addition, overcurrent phenomena such as lightning strikes may also occur in practical application scenarios, which will also pose challenges to the life and stability of the transient voltage suppressor.

Embodiments of the present disclosure provides an apparatus and method for protecting a solid-state circuit breaker, a solid-state circuit breaker, and a computer-readable storage medium, at least in part to the foregoing and other potential problems present in the prior art.

In a first aspect of the present disclosure, there is provided an apparatus for protecting a solid-state circuit breaker. The solid-state circuit breaker comprises a first switching device, a second switching device, and a first transient voltage suppression unit, the first switching device is connected in series with the second switching device, both the first switching device and the second switching device are connected in parallel with the first transient voltage suppression unit, the first transient voltage suppression unit comprises one or more transient voltage suppressors. The apparatus comprises: a temperature detection unit configured to detect a case temperature of each of the one or more transient voltage suppressors; and a control unit configured to: receive the case temperature of the one or more transient voltage suppressors from the temperature detection unit; for each of the one or more transient voltage suppressors, predict a junction temperature of each of the one or more transient voltage suppressors after the first switching device and the second switching device are switched from an on state to an off state, based on the case temperature before the first switching device and the second switching device are switched from the on state to the off state; and in response to the junction temperature of at least one transient voltage suppressor of the one or more transient voltage suppressors exceeding a predetermined temperature threshold, generate a first alarm signal.

In a second aspect of the present disclosure, there is provided a method for protecting a solid-state circuit breaker. The solid-state circuit breaker comprises a first switching device, a second switching device, and a first transient voltage suppression unit, the first switching device is connected in series with the second switching device, both the first switching device and the second switching device are connected in parallel with the first transient voltage suppression unit, the first transient voltage suppression unit comprises one or more transient voltage suppressors. The method comprises: receiving a case temperature of the one or more transient voltage suppressors from a temperature detection unit configured to detect the case temperature of each of the one or more transient voltage suppressors; for each of the one or more transient voltage suppressors, predict a junction temperature of each of the one or more transient voltage suppressors after the first switching device and the second switching device are switched from an on state to an off state, based on the case temperature before the first switching device and the second switching device are switched from the on state to the off state; and in response to the junction temperature of at least one transient voltage suppressor of the one or more transient voltage suppressors exceeding a predetermined temperature threshold, generate a first alarm signal.

In a third aspect of the present disclosure, there is provided a solid-state circuit breaker, comprising an apparatus of the first aspect of the present disclosure.

In a fourth aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon, the computer program being executable by a processor to implement a method of the second aspect of the present disclosure.

According to the embodiments of the present disclosure, it is able to diagnose working state of the transient voltage suppressors in the solid-state circuit breaker. In a case that it is necessary to turn off the switching device, a junction temperature of the transient voltage suppressor after the switching device is switched off can be predicted in advance based on a surface temperature of the transient voltage suppressor, and an alarm can be issued when the junction temperature exceeds a predetermined temperature threshold. In this way, potential safety hazards of the transient voltage suppressors can be found in a timely manner to ensure safe and reliable operation of the solid-state circuit breaker.

It should be understood that the content described in this section is not intended to limit critical or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easier to be understood through the following description.

Embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the accompanying drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

In the description of embodiments of the present disclosure, the term “including” and similar terms should be understood as open-ended inclusion, that is, “including but not limited to”. The term “based on” should be understood as “at least partially based on”. The term “one embodiment” or “the embodiment” should be understood as “at least one embodiment”. The term “some embodiments” should be understood as “at least some embodiments”. The following text may also include other explicit and implicit definitions. The terms “first”, “second”, etc. may refer to different or identical objects. The following text may also include other explicit and implicit definitions.

As mentioned above, with continuous increase of a current level in the solid-state circuit breaker and the line inductance in practical application situation, an induced voltage generated by the line inductance and beared by the solid-state circuit breaker is increasing, which brings a great challenge to the life of protection devices such as the transient voltage suppressor. In addition, overcurrent phenomena such as lightning strikes may also occur in practical application scenarios, which will also pose challenges to the life and stability of the transient voltage suppressor. Embodiments of the present disclosure provide a scheme for protecting the solid-state circuit breaker, which can diagnose a working state of the transient voltage suppressor in the solid-state circuit breaker; in a case that it is necessary to turn off the switching device, a junction temperature of the transient voltage suppressor after the switching device is switched off can be predicted in advance based on a surface temperature of the transient voltage suppressor, and an alarm can be issued when the junction temperature exceeds a predetermined temperature threshold. The principle of the present disclosure will be described below in conjunction with.

shows a circuit schematic view of a solid-state circuit breaker of some embodiments of the present disclosure.shows setting the solid-state circuit breaker only in a single-phase circuit of a main circuit as an example to describe principles of the present disclosure. It should be understood that in the embodiments of the present disclosure, the solid-state circuit breaker can be set individually for each phase circuit, or in a part of multiple phase circuits, and these implementations fall within the scope of the present disclosure.

shows an L-phase line and an N-phase line. The L-phase line is connected to a positive pole of a power supply PW, and the N-phase line is connected to a negative pole of the power supply PW and to ground GND. An isolation switch CBis provided in the L-phase line, and an isolation switch CBis provided in the N-phase line.

As shown in, the solid-state circuit breaker described here includes an input terminal IN and an output terminal OUT. The input terminal IN is connected to the isolation switch CB, and the output terminal OUT is adapted to provide an output voltage Vout to a subsequent circuit.

As shown in, the solid-state circuit breaker further includes a first switching device Qand a second switching device Qconnected in series between the input terminal IN and the output terminal OUT. The first switching device Qand the second switching device Qare respectively formed with a freewheeling diode. The first switching device Qand the second switching device Qare main circuit solid-state switches adapted to control an on-off state of the main circuit. The first switching device Qand the second switching device Qmay include various conventional or future available types. In an embodiment, the first switching device Qand the second switching device Qmay include metal oxide field effect transistors (MOSFETs), such as SiC MOSFETs. In another embodiment, the first switching device Qand the second switching device Qmay include insulated gate field effect transistors (IGBTs).

As shown in, the solid-state circuit breaker further includes a first transient voltage suppression unitconnected in parallel with the first switching device Qand the second switching device Q. The first transient voltage suppression unitmay include one or more transient voltage suppressors. In a case that the first switching device Qand the second switching device Qare switched from an on state to an off state, the line inductance can generate an induced voltage. In a case that the induced voltage reaches a certain voltage level, the transient voltage suppressorin the first transient voltage suppression unitcan be broken down, so that the first transient voltage suppression unitis switched on to prevent the first switching device Qand the second switching device Qfrom being broken down. In a case that the transient voltage suppressorin the first transient voltage suppression unitis switched on, a high current will be generated in the transient voltage suppressor. Under the action of the high voltage and high current, a temperature of the transient voltage suppressorin the first transient voltage suppression unitwill rise instantaneously.

In an embodiment, as shown in, the first transient voltage suppression unitincludes two transient voltage suppressors, namely TVSand TVS. It should be understood that the first transient voltage suppression unitmay include more or fewer transient voltage suppressorsdepending on the voltage level of the induced voltage generated by the line inductance in a case that the first switching device Qand the second switching device Qare switched off. For example, when the voltage of the induced voltage generated by the line inductance is low in a case that the first switching device Qand the second switching device Qare switched off, the first transient voltage suppression unitmay include only a single transient voltage suppressor. When the voltage of the induced voltage generated by the line inductance is high in a case that the first switching device Qand the second switching device Qare switched off, the first transient voltage suppression unitmay include three or more transient voltage suppressors.

As shown in, the solid-state circuit breaker described herein includes an apparatus for protecting the solid-state circuit breaker. The apparatus can diagnose a working state of the transient voltage suppressorin the solid-state circuit breaker, timely find potential safety hazards of the transient voltage suppressor, and ensure the safe and reliable operation of the solid-state circuit breaker. For convenience of description, the apparatus for protecting the solid-state circuit breaker can described herein also be referred to as a protection apparatus.

In some embodiments, as shown in, the protection apparatus includes a temperature detection unitand a control unit. The temperature detection unitis adapted to detect a case temperature of each transient voltage suppressorin the first transient voltage suppression unit. The control unitis adapted to diagnose the operating state of each transient voltage suppressorbased on the case temperature detected by the temperature detection unit.

In some embodiments, as shown in, the temperature detection unitincludes one or more temperature sensors, for detecting the case temperature of the corresponding transient voltage suppressor, respectively. For example, in a case that the first transient voltage suppression unitincludes two transient voltage suppressors, the temperature detection unitmay include two temperature sensors, each detecting the case temperature of the corresponding transient voltage suppressor. In a case that the first transient voltage suppression unitincludes more or fewer transient voltage suppressors, the temperature detection unitmay include more or fewer temperature sensors, for detecting the case temperature of the corresponding transient voltage suppressor, respectively.

shows an example arrangement of a temperature sensoron a transient voltage suppressoraccording to some embodiments of the present disclosure. As shown in, the temperature sensoris fixed onto a case surface of the corresponding transient voltage suppressorfor detecting the case temperature of the corresponding transient voltage suppressor. In some embodiments, the temperature sensorcan be fixed onto the case surface of the corresponding transient voltage suppressorby plastic embedment. In some embodiments, the temperature sensorcan be fixed onto the case surface of the corresponding transient voltage suppressorby a metal foil. In some embodiments, the temperature sensorcan be fixed onto the case surface of the corresponding transient voltage suppressorby a heat-resistant adhesive. In some embodiments, the temperature sensorcan be fixed onto the case surface of the corresponding transient voltage suppressorby a combination of the above fixing methods. It should be understood that, in other embodiments, the temperature sensormay be fixed onto the case surface of the corresponding transient voltage suppressorby any other suitable means, these implementations fall within the scope of the present disclosure.

As shown in, the temperature detection unitis electrically connected to the control unit. The temperature detection unitmay be connected to the control unitby a wired or wireless manner, embodiments of the present disclosure are not limited thereto.

The control unitmay receive the case temperature of each transient voltage suppressorfrom the temperature detection unit. Then, for each transient voltage suppressor, the control unitmay predict the junction temperature of each transient voltage suppressorafter the first switching device Qand the second switching device Qare switched from the on state to the off state based on the case temperature before the first switching device Qand the second switching device Qare switched from the on state to the off state. The control unitcan diagnose the working state of each transient voltage suppressorbased on the predicted junction temperature of each transient voltage suppressor. The control unitcan generate a first alarm signal in response to the junction temperature of at least one transient voltage suppressoramong the one or more transient voltage suppressorsexceeding a predetermined temperature threshold. The first alarm signal can alert an operator in any appropriate means. For example, the first alarm signal can alert the operator by at least one of sound and flash. In embodiments of the present disclosure, the predetermined temperature threshold may be preset and stored in the control unitaccording to design requirements.

In some embodiments, the control unitmay record a case temperature rise of each transient voltage suppressorin the first transient voltage suppression uniteach time the first switching device Qand the second switching device Qare switched off normally according to the actual installation situation. For each transient voltage suppressor, the control unitmay calculate an average value of multiple temperature rise records as a reference case temperature rise of each transient voltage suppressorwhen the first switching device Qand the second switching device Qare switched off for one time. Based on the obtained reference case temperature rise, the control unitmay automatically determine the change in the junction temperature of each transient voltage suppressorcaused by the switching-off process before switching off the first switching device Qand the second switching device Qeach time. In a case that the determined junction temperature exceeds the predetermined temperature threshold, an alarm may be automatically triggered before switching off the first switching device Qand the second switching device Qto alert the operator that there may be a safety hazard in the transient voltage suppressor.

In some embodiments, the junction temperature of each transient voltage suppressormay be determined by a following equation:case+delta_case*err,

It should be noted that the numbers, values, etc. mentioned above and elsewhere in the present disclosure are exemplary and are not intended to limit the scope of the present disclosure in any way. Any other suitable numbers or values are possible.

In some embodiments, the control unitmay also record the number of times that an instantaneous temperature rise occurs in the case temperature, and in response to the number of times of the instantaneous temperature rise reaching a predetermined number of times, generate a second alarm signal. The number of times of the instantaneous temperature rise represents the number of times that the transient voltage suppressorin the first transient voltage suppression unitcan withstand surges, that is, the number of times that the first switching device Qand the second switching device Qare switched off. The thickness of the PN junction (semiconductor-metal sheet) inside the transient voltage suppressorin the first transient voltage suppression unitis inversely proportional to the number of times of an avalanche breakdown. The thickness of the PN junction inside the transient voltage suppressorbecomes thinner each time a breakdown occurs. Therefore, a predetermined number of times can be pre-set and stored in the control unit. When the number of times of the instantaneous temperature rise is lower than the predetermined number of times, it indicates that the transient voltage suppressorin the first transient voltage suppression unitcan operate reliably. When the number of times of the instantaneous temperature rise reaches the predetermined number, it indicates that the transient voltage suppressorin the first transient voltage suppression unitmay pose a safety risk, so the control unitcan generate a second alarm signal to prompt the operator. In this way, the control unitcan ensure that the number of times of instantaneous temperature rise of the transient voltage suppressorin the first transient voltage suppression unitis within a specification requirement by recording the number of times of instantaneous temperature rise of the transient voltage suppressorin the first transient voltage suppression unit. The second alarm signal can alert the operator in any suitable way. For example, the second alarm signal can alert the operator through at least one of sound and flash. In embodiments of the present disclosure, the predetermined number of times can be set according to product design requirements, such as 10,000 times, 30,000 times, 100,000 times, or other values.

In some implementations, as shown in, the protection apparatus further includes a current detection unit, an input voltage detection unit, and an output voltage detection unitconnected to the control unit. The current detection unitis adapted to detect a current of the first transient voltage suppression unit. The input voltage detection unitis adapted to detect the input voltage of the first transient voltage suppression unit. the output voltage detection unitis adapted to detect an output voltage of the first transient voltage suppression unit. The control unitcan determine the voltage across the first transient voltage suppression unitbased on the input voltage and the output voltage, and determine whether the first transient voltage suppression unitoperates in a normal state based on the current of the first transient voltage suppression unitand the voltage across the first transient voltage suppression unit. In response to the first transient voltage suppression unitnot operating in the normal state, the control unitcan generate a third alarm signal. The third alarm signal can alert the operator in any suitable way. For example, the third alarm signal can alert the operator by at least one of sound and flash.

In some embodiments, a safe operation area curve, a temperature derating curve, a maximum single pulse power, and a maximum clamping voltage of each transient voltage suppressorin the first transient voltage suppression unitcan be stored in the control unitin advance.show some rated parameters of the transient voltage suppressoraccording to some embodiments of the present disclosure. As shown in, the rated voltage of the transient voltage suppressorchanges with the junction temperature. In a case that the junction temperature exceeds 50° C., the rated voltage of the transient voltage suppressorwill gradually decrease. As shown in, curveshows the voltage change of the transient voltage suppressorin the first transient voltage suppression unitupon experiencing surge, and curveshows the current change of the transient voltage suppressorupon experiencing surge. As shown in, the maximum single pulse power of the transient voltage suppressorchanges with pulse width. As shown in, the breakdown voltage of the transient voltage suppressorchanges with the junction temperature.

In some embodiments, the control unitmay determine whether the first transient voltage suppression unitoperates in the normal state. The control unitmay determine whether each transient voltage suppressorin the first transient voltage suppression unittouches at least one of the safe operation area curve, the temperature derating curve, the maximum single pulse power, and the maximum clamping voltage. In response to the first transient voltage suppression unitnot touching at least one of the safe operation area curve, the temperature derating curve, the maximum single pulse power and the maximum clamping voltage, the control unitmay determine that the first transient voltage suppression unitoperates in the normal state. In response to the first transient voltage suppression unittouching at least one of the safe operation area curve, the temperature derating curve, the maximum single pulse power and the maximum clamping voltage, the control unitmay determine that the first transient voltage suppression unithas already operated in a limit state, that is, not in the normal state. In a case that the first transient voltage suppression unithas already operated in the limit state, the control unitmay generate a third alarm signal to indicate potential risks.

The transient voltage suppressorin the first transient voltage suppression unitcannot withstand an overvoltage for a long time. For example, the longest time that the transient voltage suppressorcan withstand the overvoltage may be 10 ms or less. Therefore, when the overvoltage occurs in the solid-state circuit breaker, it is necessary to quickly trip the mechanical switch within 10 ms to protect the transient voltage suppressorand the switching devices Qand Qof the subsequent stage from damage. To this end, in some embodiments, the protection apparatus further includes a fuseand a second transient voltage suppression unit, as shown in.

As shown in, the fuseand the second transient voltage suppression unitare connected in series with the electromagnetic coil Lfor tripping the mechanical switch. The fuseis adapted to protect the second transient voltage suppression unitfrom being burned out by long-term overcurrent. The second transient voltage suppression unitmay include one or more transient voltage suppressors. In a case that a voltage across the second transient voltage suppression unitexceeds a first predetermined voltage threshold, the transient voltage suppressorin the second transient voltage suppression unitcan be switched on. In a case that the voltage across the second transient voltage suppression unitexceeds the second predetermined voltage threshold (for example, overvoltage occurs), the transient voltage suppressorin the second transient voltage suppression unitcan be switched on and the electromagnetic coil Lcan trip the mechanical switch. The second predetermined voltage threshold is higher than the first predetermined voltage threshold.

In a case that a system voltage exceeds a breakdown voltage of the second transient voltage suppression unit(i.e., the first predetermined voltage threshold, such as 860V), the second transient voltage suppression unitwill be gradually switched on, so that the current flowing through the second transient voltage suppression unitincreases gradually. The electromagnetic coil Lhas a fixed resistance value R (e.g., 8.6 ohm), which is adapted to limit the maximum current flowing through the second transient voltage suppression unit, such as 100 A. In the case of overvoltage (exceeding the second predetermined voltage threshold), the current flowing through the second transient voltage suppression unitwill flow through the electromagnetic coil L. When the current exceeds a tripping current threshold of the electromagnetic coil L, the electromagnetic coil Lwill drive the mechanical switch to trip. The entire tripping process of the mechanical switch is not affected by the control unitand other circuits. The theoretical maximum tripping time depends only on the size of the electromagnetic coil Land the mechanical delay, so the entire tripping time can be significantly reduced, for example, within 10 ms.

A flowchart of a processfor protecting a solid-state circuit breaker is described below with reference to. The processmay be performed by the protection apparatus described above, for example by the control unitin the protection apparatus.

At block, the control unitreceives a case temperature of one or more transient voltage suppressorsfrom the temperature detection unit. The temperature detection unitmay be configured as described above for detecting the case temperature of each transient voltage suppressor.

At block, for each transient voltage suppressor, the control unitpredicts the junction temperature of each transient voltage suppressorafter the first switching device Qand the second switching device Qare switched from the on state to the off state based on the case temperature before the first switching device Qand the second switching device Qare switched from the on state to the off state. The control unitmay predict the junction temperature by using the approaches described above.

At block, the control unitgenerates a first alarm signal in response to the junction temperature of at least one transient voltage suppressoramong the one or more transient voltage suppressorsexceeding a predetermined temperature threshold.

In some embodiments, the junction temperature of one or more transient voltage suppressorsis determined by an equation:

In some embodiments, the processfurther includes: recording the number of times that an instantaneous temperature rise occurs in the case temperature; and in response to the number of times of the instantaneous temperature rise reaching a predetermined number of times, generating a second alarm signal.

In some embodiments, the processfurther includes: receiving a current of first transient voltage suppression unitfrom the current detection unit; receiving an input voltage of first transient voltage suppression unitfrom the input voltage detection unit; receiving an output voltage of first transient voltage suppression unitfrom the output voltage detection unit; determining a voltage across the first transient voltage suppression unitbased on the input voltage and the output voltage; determining whether the first transient voltage suppression unitoperates in the normal state based on the current of the first transient voltage suppression unitand the voltage across the first transient voltage suppression unit; and in response to the first transient voltage suppression unitnot operating in the normal state, generating a third alarm signal.

In some embodiments, determining whether the first transient voltage suppression unitoperates in the normal state based on the current of the first transient voltage suppression unitand the voltage across the first transient voltage suppression unitcomprises: determining whether the first transient voltage suppression unittouches at least one of the safe operation area curve, the temperature derating curve, the maximum single pulse power and the maximum clamping voltage; in response to the first transient voltage suppression unitnot touching at least one of the safe operation area curve, the temperature derating curve, the maximum single pulse power and the maximum clamping voltage, determining that the first transient voltage suppression unitoperates in the normal state; and in response to the first transient voltage suppression unittouching at least one of the safe operation area curve, the temperature derating curve, the maximum single pulse power and the maximum clamping voltage, determining that the first transient voltage suppression unitdoes not operate in the normal state.

shows a block diagram illustrating an electronic devicein which one or more embodiments of the present disclosure may be implemented. It should be understood that the electronic deviceshown inis merely exemplary and should not constitute any limitation on the functionality and scope of the embodiments described herein.

As shown in, the electronic deviceis in the form of a general purpose electronic device. Components of the electronic devicemay include, but are not limited to, one or more processors or processing units, a memory, a storage device, one or more communication units, one or more input devices, and one or more output devices. The processing unitmay be an actual or virtual processor and is capable of performing various processing according to programs stored in the memory. In a multiprocessor system, multiple processing units execute computer-executable instructions in parallel to improve the parallel processing capability of the electronic device.

The electronic devicetypically includes multiple computer storage media. Such media can be any obtainable media accessible to the electronic device, including but not limited to volatile and nonvolatile media, removable and non-removable media. The memorycan be a volatile memory (such as a register, a cache, a random access memory (RAM)), a nonvolatile memory (such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory), or some combination thereof. The storage devicecan be removable or non-removable media, and can include machine-readable media such as a flash drive, a disk, or any other media that can be used to store information and/or data (such as training data for training) and can be accessed within the electronic device.

The electronic devicemay further include additional removable/non-removable, volatile/non-volatile storage media. Although not shown in, a disk drive for reading or writing from removable, non-volatile disks (e.g., “floppy disks”) and an optical disk drive for reading or writing from removable, non-volatile optical discs may be provided. In these cases, each drive may be connected to a bus (not shown) by one or more data media interfaces. The memorymay include a computer program producthaving one or more program modules configured to perform various methods or acts of various embodiments of the present disclosure.

The communication unitenables communication with other electronic devices through the communication media. Additionally, the functions of the components of the electronic devicemay be implemented in a single computing cluster or multiple computing machines that are capable of communicating through a communication connection. Therefore, the electronic devicemay operate in a networked environment using a logical connection with one or more other servers, a network personal computer (PC), or another network node.

The input devicecan be one or more input devices, such as a mouse, keyboard, trackball, etc. The output devicecan be one or more output devices, such as a display, speaker, printer, etc. The electronic devicecan also communicate with one or more external devices (not shown) through the communication unitas needed, such as storage devices, display devices, etc., communicate with one or more devices that enable users to interact with electronic device, or communicate with any device (such as a network interface card, modem, etc.) that enables electronic deviceto communicate with one or more other electronic devices. Such communication can be performed via input/output (I/O) interfaces (not shown).